The preparation of esters by reacting an epoxide with a carboxylic acid is catalyzed by the use of a strongly basic anion exchange resin and is well known technology. Especially well know is the preparation of hydroxyalkyl(meth)acrylates by reacting an alkylene oxide and acrylic or methacrylio acid. The strongly basic anion exchange resin commonly employed as a catalyst in this reaction is a macroporous resin of the styrene-divinylbenzene type. The resin may be added to the reactor in any of several forms, e.g. as either the chloride or hydroxide form. One patent which describes the use of such a resin is U.S. Pat. No. 3,340,295. A resin having a particular swelling capacity in water, a particular ion exchange capacity and a limited amount of monosubstituted aromatic rings in the polymer backbone for catalyzing the subject reaction is described in U.S. Pat. No. 3,804,884.
Strongly basic anion exchange resins have also been made from polymers having an acrylic backbone, the manufacture of which is found in numerous patents. One of the earliest of these is U.S. Pat. No. 2,630,427, which teaches reacting in aqueous medium a tertiary amine, e.g. trimethylamine, with an insoluble, cross-linked copolymer of a glycidyl ester with a copolymerizable monomer containing two or three non-conjugated vinylidene groups. A later patent, U.S. Pat. No. 2,862,893, reacts the amine with a copolymer of a chlorohydrin ester and a copolymerizable monomer which contains at least two non-conjugated vinylidene groups. U.S. Pat. No. 3,427,262 teaches crosslinking the polyacrylic structure with an aliphatic or cycloaliphatic hydrocarbon containing two or more allyl groups, e.g. hexa-1,5-diene, and, optionally, an additional crosslinking agent of a di- or trivinyl aromatic compound. The product is said to be more stable and less hydrolyzable. U.S. Pat. No. 3,551,357 also discloses a process for making a hydrolysis-resistant acrylic ester-based anion exchange resin using other divinyl aromatic crosslinkers. Additionally, U.S. Pat. No. 4,052,343 discloses a polymer which has ester functionality, and U.S. Pat. No. 4,082,701 discloses a polymer having amide rather than ester functionality which is more resistant to hydrolysis.
These strongly basic acrylic-based anion exchange resins have utility in applications such as decolorizing cane sugar syrups (U.S. Pat. No. 3,791,866), recovery of uranium complexes (U.S. Pat. No. 3,870,663), removal of dyes from waste streams and chemical and oxygen demanding wastes from pulp mill effluents (U.S. Pat. No. 4,082,701).